Creation of raw device for oracle table Space datafiles.

Creation of raw device for oracle table Space datafiles. (Unix Team Activity)

Recently the following storage has been created (on UAT):

/dev/sdao

/dev/sdap

Each of the above raw devices is hosted from the XP1024 storage array, and can accommodate 5 x 8gb devices to be allocated to the database.

The following instructions assume that the user is root, and the oracle environments are fully down.

1)     Partition the new devices using fdisk following below partition table for cylinder guidance, repeating for all new devices sdao and sdap, start on serverdb1:

# fdisk /dev/sdao

Disk /dev/sdao: 42.9 GB, 42949672960 bytes

255 heads, 63 sectors/track, 5221 cylinders

Units = cylinders of 16065 * 512 = 8225280 bytes

    Device Boot      Start         End      Blocks   Id  System

/dev/sdao1               1        1045     8393931   83  Linux

/dev/sdao2            1046        2090     8393962+  83  Linux

/dev/sdao3            2091        3135     8393962+  83  Linux

/dev/sdao4            3136        5221    16755795    5  Extended

/dev/sdao5            3136        4180     8393931   83  Linux

/dev/sdao6            4181        5221     8361801   83  Linux

And…

Disk /dev/sdap: 44.1 GB, 44197360640 bytes

255 heads, 63 sectors/track, 5373 cylinders

Units = cylinders of 16065 * 512 = 8225280 bytes

    Device Boot      Start         End      Blocks   Id  System

/dev/sdap1               1        1075     8634906   83  Linux

/dev/sdap2            1076        2150     8634937+  83  Linux

/dev/sdap3            2151        3225     8634937+  83  Linux

/dev/sdap4            3226        5373    17253810    5  Extended

/dev/sdap5            3226        4300     8634906   83  Linux

/dev/sdap6            4301        5373     8618841   83  Linux

2)     Once the above partitions tables have been added and written to serverdb1, go to serverdb2 and fdisk the same devices. The partitions tables should already be populated as per serverdb1, just ensure you write the partition tables to commit these changes.

3)     Backup /etc/DATA_RAC_RAW file on serverdb1 and serverdb2 and edit /etc/DATA_RAC_RAW to reflect the addition of the new devices, e.g.

# cp /etc/DATA_RAC_RAW /etc/DATA_RAC_RAW.preCMxxxxx

Append the following new entries in /etc/DATA_RAC_RAW onto the end of the existing files

/dev/eudata/unused24_8g:/dev/sdao1:c:162:266:8010

/dev/eudata/unused25_8g:/dev/sdao2:c:162:267:8010

/dev/eudata/unused26_8g:/dev/sdao3:c:162:268:8010

/dev/eudata/unused27_8g:/dev/sdao5:c:162:269:8010

/dev/eudata/unused28_8g:/dev/sdao6:c:162:270:8010

/dev/eudata/unused29_8g:/dev/sdap1:c:162:271:8010

/dev/eudata/unused30_8g:/dev/sdap2:c:162:272:8010

/dev/eudata/unused31_8g:/dev/sdap3:c:162:273:8010

/dev/eudata/unused32_8g:/dev/sdap5:c:162:274:8010

/dev/eudata/unused33_8g:/dev/sdap6:c:162:275:8010

4)     For each newly added device, make the character devices on serverdb1 and serverdb2

Using the above devices (repeat for all new devices), example:

# mknod /dev/eudata/unused24_8g c 162 266

# chown oracle:dba /dev/eudata/unused24_8g

Note that the minor number (266 in this case) must be unique in the OS and therefore must be incremented with each new device, 266…267… as per the above entries in the /etc/DATA_RAC_RAW file

mknod /dev/eudata/unused24_8g c 162 266

mknod /dev/eudata/unused25_8g c 162 267

mknod /dev/eudata/unused26_8g c 162 268

mknod /dev/eudata/unused27_8g c 162 269

mknod /dev/eudata/unused28_8g c 162 270

mknod /dev/eudata/unused29_8g c 162 271

mknod /dev/eudata/unused30_8g c 162 272

mknod /dev/eudata/unused31_8g c 162 273

mknod /dev/eudata/unused32_8g c 162 274

mknod /dev/eudata/unused33_8g c 162 275

5)     Bind new raw devices on both nodes, serverdb1 first, then serverdb2

Using the above example device (repeat for all new devices):

# raw /dev/eudata/unused24_8g /dev/sdao1

raw /dev/eudata/unused25_8g /dev/sdao2

raw /dev/eudata/unused26_8g /dev/sdao3

raw /dev/eudata/unused27_8g /dev/sdao5

raw /dev/eudata/unused28_8g /dev/sdao6

raw /dev/eudata/unused29_8g /dev/sdap1

raw /dev/eudata/unused20_8g /dev/sdap2

raw /dev/eudata/unused31_8g /dev/sdap3

raw /dev/eudata/unused32_8g /dev/sdap5

raw /dev/eudata/unused33_8g /dev/sdap6

-- At this point we have successfully added the new devices to Linux. The devices (“unused*”) will be ready to allocate when necessary, and can be allocated without any disruption to the Oracle environment as steps 1-5 have been completed.

6)     Release the system to the dba’s to add the new devices to oracle and test.

Linux Command History Advanced Features

Linux Command History Advanced Features

“History” command is a very important command in Linux to check the last executed commands in your system. We can use “history” command in some advanced manner with using some extra functionality. You can find this command more enjoyable by using following document.

1.    Display Time Format using HISTSIZEFORMAT

When you run simple “history” it displays only number of command and last running command. For auditing purpose the time for running command is important. Timestamp can be added in history command as shown below.

# export HISTTIMEFORMAT="%F %T "

# history | more

   1  2012-09-12 10:48:00 ls

   2  2012-09-12 10:48:07 history

   3  2012-09-12 10:48:24 ls -ltr

   4  2012-09-12 10:54:57 ls

   5  2012-09-12 10:55:05 ls -ltr

   6  2012-09-12 10:55:22 cat ff_unix

2.    Search the history using Control+R

When you’ve already executed a very long command, you can simply search history using a keyword and re-execute the same command without having to type it fully. Press Control+R and type the keyword. In the following example, I searched for red, which displayed the previous command “cat /etc/redhat-release” in the history that contained the word red.In the following example, I searched for red, which displayed the previous command “cat /etc/redhat-release” in the history that contained the word red.

# [Press Ctrl+R from the command Prompt, which will display reverse –i-search prompt.]

(reverse-i-search)`red': cat /etc/redhat-release

[Note: Press enter when you you see command, which will execute from history.]

[root@qmailprd ~]# cat /etc/redhat-release

Red Hat Enterprise Linux Server release 6.2 (Santiago)

Sometimes you want to edit a command from history before executing it. For e.g. you can search for httpd, which will display service httpd stop from the command history, select this command and change the stop to start and re-execute it again as shown below.

# [Press Ctrl+R from the command prompt,which will display the reverse-i-search prompt]

(reverse-i-search)`httpd': service httpd stop

[Note: Press either left arrow or right arrow key when you see your

command, which will display the command for you to edit, before executing it]

# service httpd start

3.    Repeat previous command quickly using 4 different methods

Sometime you may end up repeating the previous commands for various reasons. Following are the 4 different ways to repeat the last executed command.

1.    Use the up arrow to view the previous command and press enter to execute it.

2.    Type !! and press enter from the command line

3.    Type !-1 and press enter from the command line.

4.    Press Control+P will display the previous command, press enter to execute it

4. Execute a specific command from history

In the following example, If you want to repeat the command #998, you can do !998 as shown below

  997  vi pop3d-ssl

  998  pwd

  999  openssl s_client -connect localhost:993 -quiet

 1000  history

 1001  cat /etc/issue

 1002  cat /etc/redhat-realease

 1003  history

[root@qmailprd ~]# !998

pwd

/root

5. Execute previous command that starts with a specific word

Type ! followed by the starting few letters of the command that you would like to re-execute. In the following example, typing !ps and enter, executed the previous command starting with ps, which is ‘ps aux | grep http’.

[root@qmailprd ~]# !ps

ps -ef | grep http

root      1830     1  0 Aug03 ?        00:00:35 /usr/sbin/httpd

apache   22502  1830  0 Sep16 ?        00:00:00 /usr/sbin/httpd

apache   22503  1830  0 Sep16 ?        00:00:00 /usr/sbin/httpd

6. Control the total number of lines in the history using HISTSIZE

Append the following two lines to the .bash_profile and relogin to the bash shell again to see the change. In this example, only 1500 command will be stored in the bash history.

# vi ~/.bash_profile

HISTSIZE=1500

HISTFILESIZE=1500

7. Change the history file name using HISTFILE

By default, history is stored in ~/.bash_history file. Add the following line to the .bash_profile and relogin to the bash shell, to store the history command in .commandline_warrior file instead of .bash_history file. I’m yet to figure out a practical use for this. I can see this getting used when you want to track commands executed from different terminals using different history file name.

# vi ~/.bash_profile

HISTFILE=/root/.commandline_warrior

8. Eliminate the continuous repeated entry from history using HISTCONTROL

In the following example pwd was typed three times, when you do history, you can see all the 3 continuous occurrences of it. To eliminate duplicates, set HISTCONTROL to ignoredups as shown below.

# pwd

# pwd

# pwd

# history | tail -4

44  pwd

45  pwd

46  pwd [Note that there are three pwd commands in history, after

executing pwd 3 times as shown above]

47  history | tail -4

# export HISTCONTROL=ignoredups

# pwd

# pwd

# pwd

# history | tail -3

56  export HISTCONTROL=ignoredups

57  pwd [Note that there is only one pwd command in the history, even after

executing pwd 3 times as shown above]

58  history | tail -4

9. Erase duplicates across the whole history using HISTCONTROL

The ignoredups shown above removes duplicates only if they are consecutive commands. To eliminate duplicates across the whole history, set the HISTCONTROL to erasedups as shown below.

# export HISTCONTROL=erasedups

# pwd

# service httpd stop

# history | tail -3

38  pwd

39  service httpd stop

40  history | tail -3

# ls -ltr

# service httpd stop

# history | tail -6

35  export HISTCONTROL=erasedups

36  pwd

37  history | tail -3

38  ls -ltr

39  service httpd stop

[Note that the previous service httpd stop after pwd got erased]

40  history | tail -6

10. Force history not to remember a particular command using HISTCONTROL

When you execute a command, you can instruct history to ignore the command by setting HISTCONTROL to ignorespace AND typing a space in front of the command as shown below. I can see lot of junior sysadmins getting excited about this, as they can hide a command from the history. It is good to understand how ignorespace works. But, as a best practice, don’t hide purposefully anything from history.

# export HISTCONTROL=ignorespace

# ls -ltr

# pwd

#  service httpd stop [Note that there is a space at the beginning of service,

to ignore this command from history]

# history | tail -3

67  ls -ltr

68  pwd

69  history | tail -3

 

11. Clear all the previous history using option -c

Sometime you may want to clear all the previous history, but want to keep the history moving forward.

# history -c

12. Subtitute words from history commands

When you are searching through history, you may want to execute a different command but use the same parameter from the command that you’ve just searched.

In the example below, the !!:$ next to the vi command gets the argument from the previous command to the current command.

# ls anaconda-ks.cfg

anaconda-ks.cfg

# vi !!:$

vi anaconda-ks.cfg

In the example below, the !^ next to the vi command gets the first argument from the previous command (i.e cp command) to the current command (i.e vi command).

# cp anaconda-ks.cfg anaconda-ks.cfg.bak

anaconda-ks.cfg

# vi  !^

vi anaconda-ks.cfg

 

 

13. Substitute a specific argument for a specific command.

In the example below, !cp:2 searches for the previous command in history that starts with cp and takes the second argument of cp and substitutes it for the ls -l command as shown below.

# cp ~/longname.txt /really/a/very/long/path/long-filename.txt

# ls -l !cp:2

ls -l /really/a/very/long/path/long-filename.txt

In the example below, !cp:$ searches for the previous command in history that starts with cp and takes the last argument (in this case, which is also the second argument as shown above) of cp and substitutes it for the ls -l command as shown below.

# ls -l !cp:$

ls -l /really/a/very/long/path/long-filename.txt

14. Disable the usage of history using HISTSIZE

If you want to disable history all together and don’t want bash shell to remember the commands you’ve typed, set the HISTSIZE to 0 as shown below.

# export HISTSIZE=0

# history

# [Note that history did not display anything]

15. Ignore specific commands from the history using HISTIGNORE

Sometimes you may not want to clutter your history with basic commands such as pwd and ls. Use HISTIGNORE to specify all the commands that you want to ignore from the history. Please note that adding ls to the HISTIGNORE ignores only ls and not ls -l. So, you have to provide the exact command that you would like to ignore from the history.

# export HISTIGNORE="pwd:ls:ls -ltr:"

# pwd

# ls

# ls -ltr

# service httpd stop

# history | tail -3

79  export HISTIGNORE="pwd:ls:ls -ltr:"

80  service httpd stop

81  history

[Note that history did not record pwd, ls and ls -ltr]